The present disclosure relates to a battery cell including a protection circuit module assembly having a lead plate.
In recent years, as the price of energy sources is increased due to depletion of fossil fuels and the interest in environmental pollution is amplified, the demand for environmentally friendly alternative energy sources becomes an indispensable factor for the future. Various researches on power generation technologies such as nuclear power, solar power, wind power, and tidal power are continuing, and electric power storage devices for more efficient use of such generated energy are also attracting much attention.
Especially, as technology development and demand for mobile devices increase, the demand for a battery as an energy source is rapidly increasing, and in recent years, the use of secondary batteries as a power source for electric vehicles (EV) and hybrid electric vehicles (HEV) has been realized and the use area has also been expanded for use as a power auxiliary power source through a grid. Therefore, many researches are conducted on the battery that can meet various demands.
Typically, there is a high demand for a prismatic secondary battery and a pouch-shaped secondary battery which can be applied to products such as mobile phones with a thin thickness in terms of the shape of the battery and there is a high demand for lithium secondary batteries, such as lithium ion batteries and lithium ion polymer batteries, which have advantages such as high energy density, discharge voltage, and output stability in terms of materials.
In particular, since aluminum laminate sheets are used as exterior members, pouch-shaped batteries are attracting much attention due to their advantages such as small weight, low manufacturing cost, and easy shape deformation.
FIG. 1 is an exploded perspective view schematically illustrating a typical structure of a typical conventional pouch-shaped secondary battery.
Referring to FIG. 1, a pouch-shaped secondary battery 10 includes a stack-type electrode assembly 20 having a plurality of electrode tabs 21 and 22 protruding therefrom, two electrode leads 30 and 31 connected to the electrode tabs 21 and 22, respectively, and a battery case 40 having a structure for receiving and sealing the stack-type electrode assembly 20 to expose a part of the electrode leads 30 and 31 to the outside.
The battery case 40 includes a lower case 42 including a concave shaped reception portion 41 into which the stack-type electrode assembly 20 can be seated, and an upper case 43 for sealing the upper case 20 as a cover of the lower case 42. The upper case 43 and the lower case 42 are thermally welded together with the stack-type electrode assembly 20 built therein to form a sealing portion (not shown) along the outer circumferential surface of the battery case.
Moreover, FIG. 2 shows photographs in which electrode leads of a battery cell according to the related art are bent and connected to a lead plate.
As shown in FIG. 2, in the prior art, the lead plate is used to electrically connect the protection circuit module and the electrode lead of the battery cell. To efficiently optimize the internal space of the battery pack, after the electrode lead is connected to the lead plate, a process of bending the electrode lead over the sealing portion of the battery case was performed.
In addition, FIG. 3 illustrates photographs showing damages of a battery cell generated during a process of connecting an electrode lead of a battery cell to a lead plate according to a related art.
As shown in FIGS. 2 and 3, in the process of bending the electrode lead, it is easy for the operator to damage the sealing part of the battery case or the receiving part for receiving the electrode assembly, so that a short circuit may be caused by the damaged part, causing ignition, or electrolyte leakage through the damaged battery case, and problems such as an anode connection may be caused.
Specifically, in the process of bending the electrode lead, since the bending force varies depending on the operator, it has been difficult to achieve uniformity of the manufacturing quality by hand.
In addition, the damaged portion of the battery case due to the bending operation of the electrode lead is not easily visible, and after the connection, defect is not found and missed during the quality inspection of inspectors on the manufacturing line.
Further, when an insulation tape is attached to an area where damage is expected in order to prevent damage from occurring in the process of bending the electrode lead, the cost of workers and auxiliary materials may be increased.
Therefore, there is a high need to develop a technique that effectively prevents damage to a battery case, which occurs during the process of bending an electrode lead, without significantly increasing the manufacturing cost.